How do you know if your good looking as a guy?

I have a few suspicions that I am attractive, but I dont know for sure because no one has ever told me straight up"You are good looking"(except my parents, and a couple foreign girls (I couldnt figure out if it was my American citizenship that was attractive, or if they genuinely thought I was good looking and were just more vocal about it then Americans)), anyway here is the situation:

It seems like a lot of girls know who I am or want to talk to me. I came to a new college this year and I haven't yet met a lot of people but it seems like a lot of girls know me, several times while I was at clubs and other events I have started talking to girls who will inform me that we have a class together and will be able to tell me exactly where I sit in proportion to her in class, which is a little creepy since I had never even noticed her in a class with around 40 people. On several other occasions I have had mutual friends (who are girls) introduce me to their friends out of no where. One time I was standing in line at a basketball game and a friend came up and was like "Hey I want you to meet my friend" which seems awfully suspicious. The downside is that most of the girls that do this stuff aren't the best looking, which is a little unfortunate. I have also had at least 3 girls through high school and so far in college, try to get me to have sex with them (which I firmly resisted).

At the same time though no one has ever told me I am good looking, and I have never had a girlfriend. Hot girls have a million guys surrounding them and asking them out, but I am usually not surrounded by girls, and have never had a girl ask me out. I have girls get their friends to introduce them to me, but then I never hear from the girl again so I dont know if she just wanted to be friends, or if she was interested or what. How do I know if I am good looking?